Sonde

ABSTRACT

A sonde and an apparatus for the deployment thereof against a well casing is described, the sonde comprising a resilient C-shaped member ( 22 ) and at least one sensor ( 23 ).

The present invention relates to sondes, such as seismic or microseismicsondes.

Systems for permanently installing a sonde against an inner wall of apipe, such as the casing of a fluid extraction well, are known. Suchsystems are described in, for example, U.S. Pat. Nos. 5,092,423,5,181,565, 5,200,581, 5,111,903, 6,289,985 and 6,173,804. The first fourpatents describe arrangements in which the sonde is moved from aretracted position in a carrier to a position pressing against the wallbut in all cases the sonde remains mechanically coupled to the carrier.The latter patent describes a system that includes a flexible elementcarrying a sonde, which element is restrained in a compressed state toallow the assembly to be lowered into a well casing. When the assemblyhas been positioned in the well as required, the flexible, resilientelement is allowed to expand by the release of a locking mechanism thatholds the element in its compressed state. At the same time, mechanicalisolation is provided of the flexible element, and thus the sonde. Themethod of releasing the lock is to apply an overpressure within the wellcasing pipe, which operates a hydraulic ram to release it. This methodof instigating the installation of this mechanical clamping of the sondeto the well casing has a number of disadvantages. Pressurising the spacebetween the production tubing and the well casing is not a processpreferred by production well installers. Other devices, such as packers,may also be installed, and modern practice is to ‘inflate’ such devicesby means of pressurising the production tubing itself, and thushydraulically connecting the packer setting mechanism to the productiontubing, or to provide a separate hydraulic supply to ‘inflate’ them.Furthermore, this method of deploying a sonde to a well casing uses amechanismto effect the release of the compressed flexible element in aswitch-like action. Thus, there is no control of the placing of thesonde to the casing after release, thus imparting excessive shock to thesonde.

According to the present invention from one aspect, there is provided asonde comprising an expandable and/or resilient C-shaped member and atleast one sensor, the member being compressible, or having beencompressed, to bring its ends closer together.

According to the present invention from another aspect there is providedan apparatus for deploying a sensor against a well casing, saidapparatus comprising:

-   -   a) a sonde according to the first aspect of the present        invention;    -   b) means for supporting and locating the sonde inside the well        prior to deployment; and    -   c) means for releasably compressing the C-shaped member so as to        allow positioning of the sonde inside the well and subsequent        deployment.

According to the present invention from another aspect there is providedan installation for a well comprising:

-   -   a) a sonde according to the first aspect of the present        invention, said sonde being for deployment or deployed against        the inner wall of the well casing;    -   b) supporting means positioned inside the well for supporting        the sonde when not deployed; and    -   c) means for releasably compressing the C-shaped member so as to        allow deployment and/or retrieval of the sonde.

According to the present invention from another aspect there is provideda method of deploying a sonde against a well casing, said methodcomprising:

-   -   a) providing a sonde according to the first aspect of the        present invention;    -   b) compressing the C-shaped member;    -   c) positioning the sonde at the desired location inside the        well; and    -   d) releasing the C-shaped member thereby securing the sonde in        place.

Examples of the invention utilise a sonde, in the form of an expandable“C”-shaped ring clamp, which lends itself to a method wherein the sondeis inserted into a production well by compressing the sonde about alength of production tubing or other carrier, and whereby deployment andmechanical isolation of the sonde from the carrier can then easily beachieved simply by releasing the compressing mechanism. Preferredexamples of the invention utilise the pressure applied to productiontubing for the installation of other devices, such as packers, orutilise an existing hydraulic supply, typically one used forinstallation only, within a production well, to effect clamping of asonde to the well casing.

By utilising such convenient hydraulic sources, in combination with asuitable deployment mechanism, the sonde can be deployed under controlto avoid the mechanical shock that can result from the use of someexisting systems.

The present invention will now be described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 illustrates, diagrammatically and not to scale, a mechanism forclamping a sonde to a well casing, in a ‘loaded’ state, prior toclamping;

FIGS. 2, 3 and 4 illustrate alternatives to what is shown in FIG. 1;

FIG. 5 illustrates a clamping ring, housing seismic sensors and forminga sonde;

FIG. 6 shows the mechanism of FIG. 1 deployed to the casing wall;

FIG. 7 is a plan view of a C-shaped sonde according to a furtherembodiment of the present invention;

FIG. 8 is a sectional view taken along line X—X of FIG. 7 in thedirection shown;

FIG. 9 is a front view of an apparatus for deploying the sonde of FIG.7;

FIG. 10 is a sectional view taken along line Z—Z of FIG. 9 in thedirection shown;

FIG. 11 is a sectional view taken along line Y—Y of FIG. 9 in thedirection shown;

FIG. 12 is a front view of a sleeve forming part of the apparatus ofFIG. 9; and

FIG. 13 is a sectional view taken along line W—W of FIG. 12 in thedirection shown.

Referring to FIG. 1, well fluid production tubing 1 lies within a wellcasing 2. A clamping mechanism assembly comprises a cylinder 3 withhydraulic or gas rams 4, integral with an upper taper-ended cylinder 5,with ram output shafts 6 being connected to a lower taper-ended cylinder7, the cylinders 5 and 7 retaining an expandable, resilient ‘C’-shapedclamp ring 8 about tubing 1. Each ram 4 is a bore in the cylinder 5 witha piston 11 connected to the respective output shaft 6. The cylinders 5and 7 each retains a respective circlip 17, the circlips 17 being fittedin grooves inthe cylinder 3 in a compressed state. Each of the rams 4 isfed with either hydraulic fluid or gas from a pressurised source tooperate the clamping mechanism.

In the illustration shown as FIG. 1, the hydraulic fluid or gas sourcethat is pressurised to operate the clamping mechanism is supplied viapipes 9 from the production tubing 1.

Alternatively, as shown in FIG. 2, the hydraulic fluid or gas source maybe the same one that feeds packers in the well, which are pressurised atinstallation to pump up their circumferential expandable sections toseal them to the well casing. In FIG. 2, a packer 10 is connectedhydraulically (or via gas) to the production tubing 1 running throughits centre, via an orifice (not shown) in the tubing wall internal tothe packer, there being a tapping from the packer 10 to the pipes 9 tofeed the rams 4.

As a further alternative, as shown in FIG. 3, the clamping mechanism maybe operated by a separate hydraulic or gas feed via pipe 12, pressurisedat installation.

As another alternative, as shown in FIG. 4, the packer 10 may be‘inflated’ by a separate hydraulic or gas feed via pipe 13 which istapped to feed the clamping mechanism via pipes 9.

Since the mode of operation is identical for all hydraulic or gas feedsupply methods as per the above, FIGS. 1, 5 and 6 will be used todescribe further details of the operation of the clamping mechanism ofeach of the above examples.

FIG. 5 shows ‘C’-shaped ring clamp 8, i.e. the sonde, in its expandedstate. The ring clamp 8 houses as many seismic (e.g. microseismic)sensors 14, as are required to form the sonde and each circumferentialend of the ring is tapered as shown at 15. This ring 8 is held in acompressed state by the tapered ends of the cylinders 5 and 7 which areforced together by compression springs 18 acting between the ends of thecylinders 5 and 7 and rings 19 attached to the ends of the cylinder 3.

The process of installation of the sonde is as follows:

The clamping mechanism is ‘loaded’ by compressing the ‘C’-shaped ringclamp 8 to bring its ends closer together, and holding it in thiscompressed state between the taper-ended cylinders 5 and 7. At the sametime, the circlips 17 are also held in the compressed state by thecylinders 5 and 7. The ‘loaded’ clamping mechanism is lowered, alongwith other items that may also be installed at the same time, suchaspackers, down the well with the production tubing 1 passing through thecentre, until it is in the required position as shown in FIG. 1.Hydraulic or gas pressure is then applied, whereupon the hydraulic rams4 force the cylinders 5 and 7 apart, against the further compression ofthe springs 18. This releases the ‘C’-shaped ring clamp 8, housing theseismic sensors and making up the sonde, which thus expands to griptightly the inside of the well casing 2. The forcing apart of thecylinders 5 and 7 also results in the release of the circlips 17.Release of the circlips 17 prevents the cylinders 5 and 7 being forcedback together if the source hydraulic or gas pressure is removed afterinstallation. This deployed state is illustrated in FIG. 6.

A gradual increase of the source pressure will cause the rams 4 to movethe cylinders 5 and 7 slowly. As the ends of the clamp ring 8 and thecylinders 5 and 7 are tapered/chamfered, the slow movement of thecylinders 5 and 7 will allow the clamp ring 8 to expand slowly until itmates with the inner surface of the well casing 2. Thus, the deploymentof the sonde is gentle and under control through the control of thepressure rise of the hydraulic or gas source, thus avoiding mechanicalshock. The sonde is thus secured to the well casing and is alsomechanically isolated from the production tubing.

At the same time as this deployment takes place, the rest of the packersif fitted and powered by the same source, are deployed.

During the deployment of the sonde (or sondes) its or their angularposition(s) around the production tubing 1 may need to be adjusted.Thus, the pipes 9 (or pipes 9 and 12) may need to include a flexibleelement and the clamping mechanism will need to incorporate features inits design such as landing nipples, to allow the use of orientationtools, and orientation gauges, to effect adjustment of the rotationangle prior to deployment. Such features depend on the detail of thedesign and are thus not shown in the figures.

The above examples provide a method of deployment of the clampingmechanism that is intended to be permanent. However, a further advantageof the ‘chamfered edge’ feature of the invention is that removal of theclamping mechanism after deployment is possible. This is particularlyuseful if the clamping mechanism is deployed accidentally or in anincorrect position during installation. Referring to FIG. 6, removal ofthe clamping mechanism can be effected by simply moving the tubing 1which causes the cylinders 5 and 7 to drag the sonde along the casing.Thus, the clamping mechanism, complete with the clamp ring 8 forming thesonde can be removed, be it somewhat forcibly.

In addition to or as an alternative to using fluid pressure to set theclamping mechanism, there is the possibility of using a wireline tool toset the mechanism. This may be required if for some reason it was notpossible to pressurise the tubing 1. The procedure would be to deploythe or each clamping mechanism to its correct position in the well andthen run in a wireline tool through the tubing that would engage in aspecial lock. Pulling the wireline tool would release the lock and thusset the clamping mechanism.

A further embodiment of a C-shaped sonde and an apparatus for itsdeployment will now be described with reference to FIGS. 7 to 13. Thissonde 21 as shown in FIGS. 7 and 8, comprises an expandable, resilientC-shaped spring member 22 carrying a sensor vessel 23 at the end of onearm and a similarly sized dummy vessel 24 at the end of the other arm.Each of the vessels 23 and 24 is fitted into a respective vessel saddle25, 26, through which they are attached to the ends of the C-springmember 22. Each vessel saddle is also fitted with an anchor 27, 28positioned on the opposite side of the saddle from that attached to theC-spring member 22. The overall diameter of the sonde is such thatcompression of the C-spring member, by pressing the ends of the springmember towards one another, is required before the sonde can be insertedinto a well casing in which it is to be deployed.

The sensor vessel 23 comprises four seismic sensors (not shown) housedin a cylindrical aluminium pod with the sensor axes aligned at 109.47degrees to each other. The pod is in turn inserted into a cylindricalsteel pressure vessel 29, the open end of which is fitted with a cap 30.Wires from the sensors are routed, along grooves machined in the outsideof the pod, into the cap 30, and out through a high pressure tubingconnection 31. The dummy vessel 24 contains no sensors and is attachedto the C-spring member only for balance and symmetry.

Referring now to FIGS. 9 and 10, the apparatus for deploying the sondecomprises a length of production well tubing 32, typically 1500 mm inlength and male threaded at both ends for insertion into the productiontubing of a well and, which is provided with a sonde securing anddeployment mechanism. This mechanism comprises a sonde supporting sleeve33 that is rotatably mounted on the production tubing, and a sondelocking peg 34 driven by a piston 36 of a hydraulic cylinder 35 mountedon the production tubing 32 above the supporting sleeve 33. The lockingpeg 34 is forked at the end, with two tapered prongs, and is guidinglylinked to the supporting sleeve 33 by means of a cam pin 37 on the peg34 which pin 37 fits into a cam groove 38 machined on the outer surfaceof the sleeve 33.

The supporting sleeve 33 is shown in greater detail in FIGS. 12 and 13,and, as can be seen in these figures, in addition to the cam groove 38the sonde supporting sleeve 33 is provided with a pair of lower lugs 39and upper lugs 40 for supporting the sonde. The bottom end of the camgroove is closed and is positioned between and just above the upper pairof lugs. From there, the groove extends upwards, initially verticallyand then curving off to the side and up. The upper end of the groove isopen.

Referring again to FIGS. 9 and 10, in order to secure the sonde 21 tothe length of production tubing 32 the sonde is positioned around thesupporting sleeve 33 with the piston 36 fully extended such that theforked end of the locking peg 34 clamps the sonde anchors 27, 28together, thereby compressing the C-spring member 22 around thesupporting sleeve. In this position, the cam pin 37 of the locking peg34 is at the bottom end of the cam groove 38 in the supporting sleeve,with the effect that the upper and lower pairs of lugs 39, 40 on thesleeve are positioned respectively above and below the sensor and dummyvessels 25 and 26. The sonde is thus firmly held against both lateraland rotational movement relative to the length of production tubing 32.

Having secured the sonde 21 to and about the length of production tubing32, the sonde and tubing assembly can then be inserted into a wellcasing 42, with the overall diameter of the compressed C-spring sondebeing less than that of the well casing as shown in FIG. 11. Onceinserted into the well casing, signals from the sonde sensors arerelayed to the surface via a junction box 41 mounted on the productiontubing and to which the leads within the high pressure tubing 31 fromthe sensor vessel 23 are connected.

Having positioned the sonde 21 and production tubing 32 assembly insidethe well casing, deployment of the sonde 21 is effected by pressurisingthe hydraulic cylinder 35 such that the piston 36 and locking peg 34 areretracted. As the locking peg 34 retracts, the tapering of the pegprongs ensures that the clamping effect of the peg on the sonde anchors27, 28 is gradually released. Thus, by controlling the speed at whichthe piston is retracted, the rate of expansion of the C-spring member 22can be controlled, in order to prevent the sonde striking the wellcasing 42 with excessive force.

By the time the cam pin 37 on the locking peg 34 reaches the beginningof the sidewardly curved section in the cam groove 38 the locking peghas fully released the sonde anchors 37, 38, such that the now expandedC-spring member 22 firmly clamps the sonde 21 in place against the innerwall of the well casing 42. As the peg 34 continues to retract, themovement of the cam pin 37 along the curved section of the can groove 38causes the supporting sleeve 33 to rotate about the production tubing32, which in turn brings the upper and lower pairs of lugs 39, 40 out ofcontact with the sensor and dummy vessels 23, 24. Complete mechanicalisolation of the sonde from the production tubing is thereby achieved.

1. An apparatus for deploying a sensor against a well casing, saidapparatus comprising: a) a sonde comprising an expandable and/orresilient C-shaped member and at least one sensor, the member having anannular configuration with a single gap that defines two ends facingeach other, the member being compressible, or having been compressed, tobring its ends closer together; b) means for supporting and locating thesonde inside the well prior to deployment: and c) means for releasablycompressing the C-shaped member so as to allow positioning of the sondeinside the well and subsequent deployment.
 2. An apparatus according toclaim 1, which is such that deployment of said sonde is reversible sothat said sonde may be removed.
 3. An apparatus according to claim 1,wherein the means for supporting the sonde prior to deployment compriseproduction tubing for insertion or inserted into the well casing.
 4. Asonde comprising: an expandable and/or resilient C-shaped member and atleast one sensor, the member being compressible, or having beencompressed, to bring its ends closer together; means for supporting andlocating the sonde inside the well prior to deployment: and means forreleasably compressing the C-shaped member so as to allow positioning ofthe sonde inside the well and subsequent deployment; and wherein themeans for releasably compressing the C-shaped member comprise a toolhaving a surface which co-operates with a surface of the C-shaped memberto hold the C-shaped member in a compressed state.
 5. An apparatusaccording to claim 2, wherein the co-operating surfaces are shaped suchthat compression and decompression of the C-shaped member can beeffected in a controlled gradual manner.
 6. An apparatus according toclaim 5, wherein the C-shaped member has a chamfer at a circumferenceand the tool has a chamfered surface that acts on said chamfer to holdthe C-shaped member in a compressed state.
 7. An apparatus according toclaim 5, wherein the C-shaped member comprises one or more anchorportions and the tool comprises on or more pegs adapted to engage saidanchor portion or portions.
 8. A sonde comprising: an expandable and/orresilient C-shaped member and at least one sensor, the member beingcompressible, or having been compressed, to bring its ends closertogether; means for supporting and locating the sonde inside the wellprior to deployment: and means for releasably compressing the C-shapedmember so as to allow positioning of the sonde inside the well andsubsequent deployment; and the apparatus employing or being employablewith fluid pressure derived from production tubing or a separatepressure source to effect deployment of the sonde.
 9. A sondecomprising: an expandable and/or resilient C-shaped member and at leastone sensor, the member being compressible, or having been compressed, tobring its ends closer together; means for supporting and locating thesonde inside the well prior to deployment: and means for releasablycompressing the C-shaped member so as to allow positioning of the sondeinside the well and subsequent deployment; which is such that deploymentof said sonde is reversible so that said sonde may be removed; andwherein the compressing means are further adapted to compress and thusretrieve said sonde once deployed.
 10. A sonde comprising: an expandableand/or resilient C-shaped member and at least one sensor, the memberbeing compressible, or having been compressed, to bring its ends closertogether; means for supporting and locating the sonde inside the wellprior to deployment: and means for releasably compressing the C-shapedmember so as to allow positioning of the sonde inside the well andsubsequent deployment; wherein the means for supporting the sonde priorto deployment comprise production tubing for insertion or inserted intothe well casing; and wherein the sonde is at least partially supported,in its compressed stated, by one or more lugs associated with theproduction tubing.
 11. An apparatus according to claim 10, wherein theapparatus further comprises means for disengaging the lug or lugs fromthe sonde after the sonde has been deployed against the well casing. 12.An apparatus according to claim 11, wherein the lug or lugs are disposedon a sleeve mounted on the production tubing, disengaging of the lugsfrom the sonde being effected by rotation of the sleeve about thetubing.
 13. An apparatus according to claim 11, wherein the means forreleasably compressing the C-shaped member are further adapted,subsequent to the release of the C-shaped member and consequentdeployment of the sonde, to disengage the lugs from the sonde.
 14. Amethod of deploying a sonde against a well casing, said methodcomprising: a) providing a sonde comprising an expandable and/orresilient C-shaped member and at least one sensor, the member having anannular configuration with a single gap that defines two ends facingeach other; b) compressing the C-shaped member thereby bring the endscloser to each other; c) positioning the sonde at the desired locationinside the well; and d) releasing the C-shaped member thereby securingthe sonde in place.
 15. A method of deploying a sonde against a wellcasing, said method comprising: a) providing a sonde comprising anexpandable and/or resilient C-shaped member and at least one sensor, themember being compressible, or having been compressed, to bring its endscloser together; b) compressing the C-shaped member; c) positioning thesonde at the desired location inside the well; d) releasing the C-shapedmember thereby securing the sonde in place; and wherein fluid pressurederived either from production tubing or a separate pressure source isused to deploy the sonde.
 16. A method according to claim 15, whereinsuch fluid pressure is used and controlled gradually to deploy saidsonde gradually.